The present invention relates in general to candles, and in particular to a new and useful candle with a heat barrier which is partly or entirely clear or transparent, and a medium outside the barrier which is clear or transparent and which either contains one or more decorative items, or is free of everything but the medium.
The clear medium and a wax or wax-like fuel material for burning which is inside the barrier, may be any one of a variety of clear waxes or wax-substitutes such as one of the ester-terminated polyamides (ETPA) disclosed in U.S. Pat. No. 5,998,570 to Pavlin, et al. issued Dec. 7, 1999 or U.S. Pat. No. 5,783,657 to Pavlin, et al. issued Jul. 21, 1998, which are both incorporated here by reference. An example is a product known by the trademark UNICLEAR for an ETPA sold by the owner of these patents.
See also U.S. Pat. No. 5,578,089 for another clear candle material which can be used for the present invention.
U.S. Pat. No. 6,214,063 teaches candle products with etpabased icons, and is also incorporated here by reference.
U.S. Pat. No. 2,354,343 discloses a shield or barrier made of non-flammable metal or plastic material that is opaque of transparent and that is inserted into the body of a large diameter candle. A particular plastic that is disclosed for use in ethyl cellulose and similar compositions.
U.S. Pat. No. 3,741,711 discloses a pillar candle having a glass cup supporting a combustible portion of the candle inside a cylinder of insulating material and a second, larger cylinder of glass. The glass cylinder is embedded in an outer body of candle material. The glass cup does not extend the entire depth of the pillar candle. The insulating and glass cylinders are covered by a thin layer of candle material to hide them from view. The rim of the glass cup is visible on the top of the candle.
U.S. Pat. No. 5,395,233 teaches a pillar candle having an outer shell of wax, an intermediate cylindrical layer of transparent wax and potpourri and an inner core comprising a combustible candle with a wick. The inner core has a sufficiently large diameter that the intermediate and outer layers do not melt or burn. The candle does not include a barrier.
Patents teaching patterns illuminated by candle flames include U.S. Pat. No. 3,773,460 for a clear wax candle having an optical lens. In one embodiment of the candle, a lens insert made of wax is positioned in the candle below the wick which can be used to project an image and diffuse light from the candle flame. When the exposed surfaces of the lens cavity are pigmented, a pattern can be generated which reflects onto the outer surface of the candle.
U.S. Pat. No. 589,173 teaches a toy having a pattern cylinder with pattern openings that permit light from a candle burning inside the pattern cylinder to pass through onto spaced screens mounted on an outer frame. Heat rising from the candle is used to turn the pattern cylinder on an axis about the candle, so that the images formed by the pattern openings will move across the screens. The candle is a simple taper candle with a large air space between the candle and the pattern cylinder. The screens are also separated from the pattern cylinder by a gap.
A lampshade having a hidden image when the light source it is near is turned off is covered by U.S. Pat. No. 5,975,725. A design or pattern is held between inner and outer layers of the lampshade to hide the design when the shade is not being illuminated.
A candle having a non-combusting light source, such as a light bulb, inside the candle for illuminating the candle is taught by U.S. Pat. No. 3,761,702. The bottom of the candle is hollowed out and replaced with a light source. In one embodiment a clear sheath is inserted into the hollow. The sheath is disclosed as possibly having special light distributing or filtering qualities for light emanating from a light source contained therein.
A safety night light having a metal shield embedded in a glass container for a candle is disclosed by U.S. Pat. No. 2,315,803. The metal shield can have a pattern such as a mesh or honeycomb or spaced holes which light from the candle flame can pass through. The shield is a layer between the surfaces of the glass holder; the only candle material present is the candle inside the glass holder.
U.S. Pat. No. 3,077,981 teaches a candle having a design painted on the outer surface of a container which is illuminated by the candle flame inside the container. A disposable mailing tube for the candle is also provided which may have a similar design to that on the candle container. The mailing tube is discarded before using the candle.
Other patents of interest include U.S. Pat. No. 3,744,957 for a candle made of an opaque wax which turns transparent when it melts. A disk with a design is placed just below the top surface of the candle around the wick, so that when the top layer of wax is heated by the candle flame, the disk is revealed.
U.S. Pat. No. 6,033,210 discloses a candle with wax core and surrounding gel components in a clear mineral oil gel, has no barrier around the core.
A flame-resistant and retardant barrier is needed, that can be easily molded and formed. Plastics are a material which can be easily molded and formed, but which can also combust and produce very toxic by-products. Thermoplastics ordinarily have a low melting point because their structure is not highly cross-linked. In fact, most thermoplastics such as polyethylene and polypropylene are held together by weak dispersion forces causing them to act much like molecular solids (e.g., flexible, low strength, low melting point). Because the tensile strength of a polymer tends to degrade with increasing temperature, a thermoplastic such as polyethylene or polypropylene will melt or flow when heated by a flame. Polyethersulfone (PES) is an ideal material for a barrier because it is a transparent thermoplastic that is easily molded and formed, but also is uniquely and inherently a flame-retardant.
A widely accepted test to determine flammability of plastics used in products is found in Underwriter Laboratories UL-94 standard. A material is only considered flame-retardant if it meets the UL flammability standards, in which a product satisfying the V-0 standard is considered to have the highest flame resistance. ASTM standard 3801-96 and ISO standard 1210-1991 are similar standards having similar tests and equivalent ratings.
The UL-94 standard includes horizontal and vertical burn tests which can be used to rate the flammability of plastics. The vertical burn test is considered more stringent and a plastic can receive one of several ratings, depending on its flammability.
A rating of V-0 from the UL-94 vertical burn test indicates that combustion of the product stops within ten seconds after two applications of ten seconds each of a flame to a test bar of the plastic material, and the material must not produce any flaming drips. The V-0 rating is considered one of the best ratings of non-flammability for a plastic.
The UL-94 vertical burn test is performed by suspending a xc2xd inch wide by 5 inch long test rod of the plastic material over a cotton pad. A burner flame is applied to the lower end of the test rod for ten seconds, following which combustion of the rod, if any is observed until it stops. The burner flame is applied to the test rod for a second period of ten seconds. Observations of the test rod following application of the flame determine the rating the material will receive. In addition to the requirements noted above, the specimen must not begin glowing or flaming combustion after application of the burner flame. The rating for the material is based on the thickness of the test rod used. That is, a xc2xc inch thick test rod which achieves a V-0 rating qualifies the material of the test rod used in products in xc2xc or greater thicknesses. The thinner the test rod, the less combustible the material.
Polyethersulfone is one such material which has a V-0 rating for the UL-94 vertical burn test at a thickness of 0.8 mm, or about {fraction (1/32)} inches. Polyethersulfone is commonly used for electrical applications such as wire insulation, connectors, molded interconnects and housings for starters. Polyethersulfone is also known for use in other applications as well where heat resistance is desired. However, while the combustion characteristics of polyethersulfone are known, PES is not known for use in applications involving open flames.
An object of the present invention is to provide a pillar or jar candle having a flame barrier that is at least partly clear and which fits around a core of the candle and having a wick therein so that the core material can be burned. The barrier and core candle are surrounded by an outer solid body of clear candle material, for example, of wax or UNICLEAR material. The barrier is made of polyethersulfone so as not to be combustible and prevents the outer body, as well as anything embedded in the outer body, from burning. Thus, the pillar candle has the outer appearance of a candle, but will not burn and change shape or design. In likewise fashion, the jar candle of the invention, that is a candle contained in a glass or other contained, may include decorative features which are protected from the heat of the burning wick, and which may even be advantageously illuminated by light from the candle flame.
The barrier material, when entirely clear, appears essentially invisible inside the outer candle body when the fuel inside the barrier is also clear. Though many plastics are ideal because of their transparent qualities, they must also be resilient to the effect of temperature created by a candle flame. The material used for the barrier is selected for a melt point that is higher than the temperature of heat generated by the flame of the core candle. In particular, the preferred material for the barrier is polyethersulfone, which is a thermoplastic polymer that softens at about 215xc2x0 C. and melts at about 230xc2x0 C. PES is capable of withstanding temperatures much higher than most typical thermoplastics such as polyethylene and polypropylene. A very favorable feature of polyethersulfone is that it is intumescent. That is, when PES is heated, such as by a candle flame, it begins to swell and form a heat shield. PES is substantially non-combustible, having a UL-94 standard vertical test burn rating of V-0 for very thin sections.
PES is a favorable material for several other reasons. The shape of the barrier may be varied to control the burn of the core candle. The barrier may taper toward the bottom, for example, rather than being a straight-sided cylinder or have another cross-sectional shape.
Another object of the present invention is to provide a pillar or jar candle having a flame barrier having a design painted or otherwise included onto one of the barrier surfaces and surrounded by a relatively clear outer candle shell. A paper or other translucent wrapping around the outer shell acts like a screen for receiving a projected image from the barrier pattern by light from the inner core as the candle burns. Light from the flame is projected through the unpainted or clear portions of the barrier onto the paper wrapping on the outer shell.
The barrier is preferably a clear plastic material which permits light to pass through. The design which is projected onto the paper screen is formed by painted opaque portions of ink or paint preferably on the outer surface of the barrier (away from the flame) and unpainted clear portions. UNICLEAR ETPA is a preferred material for the outer shell since light from the flame can pass through the clear unpainted portions of the barrier and through the shell while the opaque portions block the light. As the candle burns down, more light or more of the design will be apparent. If the inner core candle is transparent or translucent as well, the design is projected by light from the flame passing through the inner core to the barrier even before the core burns down.
The candle of the invention does not have any air gaps between layers; each layer is in direct contact with the adjacent layer. The invention takes advantage of the transparent properties of the candle materials used to project the image from the barrier between the inner core candle and outer shell.
As noted, a preferred barrier is made of PES. In an alternate embodiment, the design is painted onto the inner surface of the barrier as a negative image. The inner core candle is placed or poured inside the painted barrier and then surrounded by a pour of UNICLEAR ETPA. An opaque wax can be used to cover the top edges of the layers to give the appearance of a conventional pillar candle. The outside is then covered with the paper or other wrap that has been treated with a fire retardant coating and glued in place. The wrap may be applied directly to the rigid outer surface of the pillar candle of the invention, or onto or inside a glass or other clear container for the jar candle of the invention.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.